Use the maze shown on the right, it makes running backwards easier, yet has good enough turns to keep Chargers slowed.

You have to be quick with weapon changes (while running!)

Hitting weak spots is a requirement.

The basic rotation for weapons is use your freeze gun primary (slow), switch to sniper rifle and use all sniper bullets then switch to assault gun and use grenades or bullets without overheating it until either freeze gun or sniper rifle is ready.

start to slow enemies immediatly when they are within range; learn at which angle you need to fire your freeze gun slow to hit the first creeps that are far away. They spawn pretty far for your slow to hit, so take this time to snipe what you can.

Note that the freeze gun recharges very slowly, so it is possible to pull off 2 grenades from the assault before the freeze is ready, just wait for the charge to below 49% before firing the second grenade.

Note on Soakers: If you are not able to kill them as mentioned in the guide, do not switch to using the above rotation so soon, but spend additional time with the assault to build damage. Keep extending the time until you get it right.

24 Chargerstactic: sniper their weak spots and slow them while the sniper is reloading, try to get a few kills from the middle lane by standing on top of the first row of blocks and sniping them when they spawn.difficulty: medium

1 Soakertactic: Once within range, immediately slow and then proceed to punch holes in his glowly weakspot with the assault. Time your slows so you don't waste valuable time switching weapons and let the slow run its full duration. I slow every time my assault hits 30%. About 3/4 into the maze, use the rotation mentioned above instead. You might need the full maze to kill him. If he is extremely near your core, use your secondary freeze gun instead to stop him (long cooldown, but at that point it does not matter).difficulty: medium/hard

36 Walkers + 18 Hovererstactic: sniper walkers once they spawn and ignore the hoverers. Once their within range of the freeze gun, apply the rotation with grenades until all walkers are dead, then go for the Hoverers. Your sniper should be one-hitting them in the weakspot.difficulty: easy/medium

15 Gliderstactic: Snipe them the moment they appear, they have low health so a weakspot hit is not needed to kill them with your level 6 sniper. They move a lot, so wait for them to stablize their path if you are not good with sniping. It is even possible with a level 5 sniper if you can hit their weakspots.difficulty: easy/medium

3 Soakers + 18 Hovererstactic: take early pot shots with the assault on the nearest soaker, then proceed to slow the entire group. Focusing on the nearest soaker. Once the hoverers step infront of the soaker you are targetting (you will notice many of your shots dealing 0 damage instead of nice red numbers), kill off the hoverers like in wave 4, then continue with the soakers like in wave 9 (They have lower health than the one in wave 9).difficulty: hard

36 Walkers + 50 Spore Podstactic: snipe the first few spore pods that spawn, until the 3 lanes of walkers meet, then proceed to kill them instead with snipes, grenades, and slows. Once dead, teleport to the bottom right televator and start sniping the pods, switching to assault to those that reach the core, don't bother with grenades unless you are really good with them. Attempt to lob the slows at the pods just behind the head of the pack if possible. difficulty: medium/hard

5 Tanks + 3 Soakerstactic: Start by sniping the tanks from far, wittling their health and hopefully killing a couple before the soakers get within range, then proceed like in wave 9 until they are all dead, then snipe the remaining tanks.difficulty: medium/hard

50 Spore Pods + 15 Gliderstactic: Ignore the gliders, your towers should be enough to kill them, focus on taking 1 snipe per spore pod, which will leave them with a tiny bit of health, then let the towers finish them off. Watch out for spore pods that float very high up and out of reach from the towers, press tab once in awhile to check if you need to teleport to your core and kill stragglers.difficulty: medium/hard

18 Hoverers + 50 Spore Podstactic: same as wave 15, snipe the pods (don't finish them off, let your scatters do that) until the hoverers are in range, then proceed to snipe/slow hoverers until they are all dead then kill off the remaining spore pods.difficulty: medium/hard

1 Soaker + 50 Spore Podstactic: same as wave 23, focus on the soaker like in wave 9 once its within range then back to the spores once its dead. You might let one spore pass, so keep trying until you get it right. difficulty: pretty hard